Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/021—Measuring pressure in heart or blood vessels
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
  • A61B5/02438—Detecting, measuring or recording pulse rate or heart rate with portable devices, e.g. worn by the patient
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
  • A61B5/02444—Details of sensor
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M21/00—Other devices or methods to cause a change in the state of consciousness; Devices for producing or ending sleep by mechanical, optical, or acoustical means, e.g. for hypnosis
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
  • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
  • A61B5/7207—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts
  • A61B5/721—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/50—General characteristics of the apparatus with microprocessors or computers
  • A61M2205/52—General characteristics of the apparatus with microprocessors or computers with memories providing a history of measured variating parameters of apparatus or patient

Definitions

• the field of the invention is that of determining one or more physiological information representative of the state of a human or animal subject. More specifically, the invention relates to an autonomous device, at least as far as the measurement reading is concerned, and capable of providing physiological information continuously.
• a particular field of the invention is that of sleep analysis, and in particular of the recognition and quantification of the different phases of sleep in a subject.
• the invention relates to an autonomous and portable device for recognizing sleep phases.
• the technology for acquiring biological signals in these systems is complex and uncomfortable for the patient. It is based on the use of a series of electrodes fixed on the patient's body, and connected to a treatment unit. The mere presence of these electrodes and their connecting cables can disturb the patient's sleep, especially if it is a person suffering from sleep disorders. This therefore introduces a bias into the measurements made. This bias is generally further aggravated by the fact that the patient is in a particular environment (hospital room) which is not usually his own. In the general public domain, there is currently no affordable and comfortable device for regular monitoring of sleep phases.
• This device is based on the use, in a portable box, of a cardiac activity sensor making it possible to follow the pulse of the subject. Knowing that the heart rate varies according to the different phases of sleep, their recognition is then, in principle, easy.
• an objective of the invention is to provide a device for determining physiological information, which is ambulatory, that is to say autonomous and portable or, more precisely, which does not hinder movements and displacements of the wearer.
• the invention aims to provide such a device which requires neither electrodes on the subject's body, nor wire connections with an external system.
• Another object of the invention is to provide such a device, which can be used anywhere, and in particular in the usual environment of the carrier subject.
• the invention also aims to provide such a device which can be used over long periods (several days), or even permanently.
• An important objective of the invention is to provide such a device determining one or more physiological data continuously, and not at widely spaced intervals, or on demand.
• a particular objective of the invention is to provide such a device capable of ensuring the recognition of sleep phases, and more generally of all the information related to sleep or drowsiness.
• the invention aims in particular to provide such a device, which offers sufficient reliability to be able to be used in the medical field. For such applications, a recognition success rate of at least 80%. and preferably 85%, is desired.
• Another objective of the invention is to provide such a device having a low cost price, in particular compared to polysomnographs.
• a specific objective of the invention is also to provide such a device, which can be easily produced industrially, and using only known means, current and inexpensive.
• the invention also aims to provide such a device, which is simple to use, and which, in particular, does not require any particular medical or technical knowledge.
• Another object of the invention is to provide such a device capable of collecting several physiological data simultaneously, and in particular data never previously collected by such devices. Consequently, the invention also aims to provide such a device, making it possible in particular to recognize and quantify the sleep phases, but also to ensure a large number of new applications, in numerous medical fields and the general public.
• a device for determining physiological information comprising:
• a first sensor placed in contact with the skin of a subject and reacting in particular to variations in the instantaneous blood pressure of said subject, delivering a signal representative of said instantaneous blood pressure, - a second sensor isolated from the skin of said subject and reacting to movements of said subject, delivering a signal representative of said movements,
• said reduction means for reducing the disturbances present in said signal representative of the instantaneous blood pressure due to said movements, as a function of said signal representative of said movements, said reduction means delivering a corrected signal
• means for processing and analyzing said corrected signal, delivering at least one of the information belonging to the group comprising:
• the invention makes it possible to determine at least one datum representative of the blood pressure or of the respiration, in a simple and inexpensive manner. Indeed, these data are not obtained directly, as is usually done, but from a suitable analysis of the instantaneous blood pressure signal, which is easy to note and which requires only one measurement on the patient's body.
• the device of the invention makes it possible in this way to obtain information continuously.
• said means for reducing disturbances comprise:
• Adaptive digital filtering means of said first corrected signal looking for correlations between said first corrected signal and said signal representative of said movements and removing in said first corrected signal the elements corresponding to said correlations, so as to deliver a second digital corrected signal.
• said sensor comprises a first piezoelectric element reacting in flexion and / or in traction / compression to the displacements of a first sensor-plate in direct contact with the body of said subject and producing a first potential difference as a function of said displacements of the first plate sensor, and a second piezoelectric compensation element reacting in flexion and / or in traction / compression to the movements of a second plate sensor isolated from the body of said subject and producing a second potential difference as a function of said movements of the second plate sensor.
• piezoelectric sensors have the advantage of a small footprint and good sensitivity. They are moreover passive, and without physiological harmfulness.
• said first and second piezoelectric elements are substantially identical and placed in spaced overlap. Thus, they undergo substantially the same movements.
• said first and / or said second piezoelectric elements are placed above and / or below a recess formed in a printed circuit and fixed to said printed circuit by their ends , using a conductive adhesive.
• the device delivers at least information representative of the relative blood pressure
• it advantageously comprises means for measuring the pressure of application of said first sensor to the body of said subject, delivering a signal representative of said pressure of application , said processing and analysis means correct said information representative of the relative blood pressure as a function of said signal representative of the application pressure.
• this application pressure can vary over time (movement of the bracelet on the wrist for example). However, it must not lead to changes in the interpretation of the measured signal.
• the processing means performs a correction, for example of the homothetic type, as a function of the application pressure.
• the device comprises positioning and / or fixing means by clamping in contact with the body of said subject of said case, such as a bracelet.
• said measuring means comprise for example a sensor reacting to the voltage of said positioning and / or clamping means.
• Said processing and analysis means may in particular comprise means for calculating the relative arterial pressure of said subject comprising at least one of the means belonging to the group comprising:
• the device of the invention comprises means for determining at least one of the information representative of the actimetry of said subject belonging to the group comprising:
• the device of the invention comprises means for determining at least one item of information representative of the breathing of said subject, from an analysis of the maxima and / or minima of said signal representative of said instantaneous blood pressure.
• the device can comprise at least one of the means belonging to the group comprising:
• the device also comprises means for calculating the heart rate of said subject.
• said means for calculating the heart rate include means for determining the period of the fundamental of said signal representative of instantaneous blood pressure.
• It may for example be multichannel filtering means comprising a plurality of filters each having a distinct frequency band, and means for detecting the filter corresponding to said fundamental period.
• the device of the invention comprises means for memorizing a series of relative blood pressure values and / or a series of heart rate values and / or a series of values representative of the actimetry and / or a series of data representative of the respiratory amplitude and / or a series of data representative of the respiratory period.
• the device comprises means for analyzing at least one of said information as a function of at least one reference value, so as to provide information representative of a state of said subject, and for example a sleep phase.
• the device advantageously comprises means for programming an approximate instant and a sleep phase, making it possible to wake up during this sleep phase.
• the device may further comprise at least one of the means belonging to the group comprising: - display means; - clock ;
• the device comprises on the one hand an autonomous portable box, comprising at least said sensors, and on the other hand remote processing means, comprising at least part of said processing and analysis means, said housing further comprising radio transmission means and said remote processing means further comprising reception means, so as to allow the transmission of the signals detected by said sensors.
• This embodiment corresponds in particular to medical applications (several autonomous units that can then be controlled by the same processing means), and more generally to all applications requiring significant storage and / or processing capacities.
• This device can be used for many applications, such as:
• FIG. 1 is a block diagram presenting the general principle of the device of the invention
• FIG. 2 illustrates an advantageous embodiment of the invention, in which piezoelectric sensors are directly bonded to the printed circuit
• - Figure 3 is the equivalent electrical diagram of the piezoelectric sensors of Figure 2
• Figure 4 shows the different sensors used according to the invention, in the case of a device in the form of a wristwatch
• - Figure 5 is a detailed block diagram of an advantageous embodiment of the invention
• FIG. 6 presents an example of a blood pressure signal
• FIG. 1 is a block diagram presenting the general principle of the device of the invention
• FIG. 2 illustrates an advantageous embodiment of the invention, in which piezoelectric sensors are directly bonded to the printed circuit
• - Figure 3 is the equivalent electrical diagram of the piezoelectric sensors of Figure 2
• Figure 4 shows the different sensors used according to the invention, in the case of a device in the form of a wristwatch
• - Figure 5 is a detailed block diagram of an advantageous embodiment of the invention
• FIG. 7 illustrates the principle of recognizing the phases of sleep (in a simplified example limited to taking into account the respiratory parameters);
• FIG. 8 is an example of a statement obtained using the device of the invention;
• Figure 9 is a block diagram illustrating the operation of the device of the invention.
• the invention therefore relates to the determination of physiological signals, essentially from the analysis of a signal representative of the variations in instantaneous blood pressure.
• the parameters that this device makes it possible to determine are in particular the heart rate, the relative arterial pressure, the respiratory amplitude, the respiratory rate, the actimetry.
• heart rate expressed in Hz
• pulse expressed in number of beats / min: at rest for a healthy individual, it is of the order of 70; for a top athlete, the value varies depending on the effort. For a cyclist, we could note a pulse passing from 45 at rest to 180 during full effort; during sleep, the pulse value varies. It is stable in deep slow sleep and fluctuates in deep sleep.
• the following variations have for example been encountered in a healthy individual: standard deviation less than 2 for 20 min in the first phase of deep slow sleep; standard deviation greater than 5 for 30 minutes of REM sleep.
• blood pressure is characterized by the value of systolic (high value) (SBP), diastolic (DBP) (low value), and average (MBP) pressures. But only the variations of these quantities are representative of the current sleep stage. Consequently, take into account a value proportional to SBP - DBP enough.
• actimetric parameters acceleration and energy.
• the acceleration existing in the three directions can be reduced to the average acceleration in a preferred direction which is approximately that perpendicular to the internal face of the wrist to account for the pendulum movement.
• the square of this speed is a function of the energy involved in the movement of the wrist.
• the acceleration While awake, the acceleration may be low while the speed is high. In stressful situations, the acceleration is strong, and the speed is slow. The amplitudes observed are specific to the individual.
• the actimetric parameters are practically zero while in REM sleep they are important (in a ratio of 1 to 5).
• the invention can in particular apply to the recognition and / or quantification of sleep phases. It is this application which is described more widely below, without this being limiting the scope of the invention. The same procedures can be implemented for any other application, and in particular those listed below.
• a night's sleep can be divided into 4 to 6 cycles, the duration of which varies from 60 to 120 minutes depending on the individual, and depending on the state of fatigue or stress of these individuals.
• Each of these cycles can be broken down into three types of phase: light slow sleep, deep slow sleep, REM sleep and wakefulness.
• Slow light sleep occurs several times per cycle. It is essentially a transition phase between awakening and another phase, or between two other phases.
• Deep slow sleep occurs especially during the first cycle. Its duration decreases sharply during the following cycles. It is physical recovery sleep. Its duration depends on the efforts of the day. Thus, after sleep deprivation, its duration compared to the other phases goes from 20% to 40%. The amount of slow deep sleep per night is substantially invariant depending on the type of sleeper (short or long sleeper). During this phase, memorization is reinforced, and dreams are generally made up of brief rational elements.
• the awakening from deep slow sleep is followed by a more or less long phase of confusion accompanied by disorientation and memory failure.
• REM sleep is the main period of dreams. Muscle tone is then completely abolished, and rapid eye movements are noticeable. Dreams during this period are long, lively and stranger than during deep sleep. They belong more to the area of affectivity.
• Waking up during this sleep period can cause stress.
• the body is then numb.
• the heart rate is very relevant information for the recognition of sleep phases.
• the use of this single information does not make it possible to obtain a rate of good recognition greater than 70%.
• This problem is particularly crucial for the measurement of blood pressure.
• This measurement is conventionally done using a tourniquet with progressive tightening and loosening requiring a sensor held by a cuff around the arm or a finger and additional management means.
• This type of tourniquet has several disadvantages: they are expensive and cumbersome, they disturb the sleeper in his sleep and above all they do not give information continuously.
• the tourniquet in polysomnographs, the tourniquet must be activated at regular intervals (for example every 10 minutes) to deliver a measurement. No data is obtained between these two intervals. It is therefore not possible to know precisely the moment of phase change, or to detect a temporary awakening ...
• the tightening of the tourniquet it is common for the subject to wake up (in particular if they have trouble sleeping). The measurement is then distorted.
• breathing varies according to the phases of sleep, as already mentioned.
• it is proposed to determine blood pressure and / or respiratory data continuously.
• Figure 1 illustrates the general principle of the device of the invention.
• a sensor 11 intended to be applied against the subject's body, detects the movements 12 of the part of the body where it is applied.
• the sensor 11 delivers an electrical signal 13, representative of these movements.
• the sensor 11 therefore detects on the one hand the movements of the subject, and on the other hand the movements of the skin corresponding to the variations in blood pressure in a blood conduit near the sensor.
• the signal 13 notably includes information representative of the variations in blood pressure.
• This signal 13 is then processed in processing means 14, so as to extract the following information therefrom: information representative of the blood pressure 15; information representative of the heart rate 16; - information representative of the actimetry 17; information representative of the respiratory amplitude 111; information representative of the respiratory frequency 112. As will be seen later, one of this information may not be considered, in a degraded embodiment.
• information representative of the blood pressure 15 information representative of the heart rate 16; - information representative of the actimetry 17; information representative of the respiratory amplitude 111; information representative of the respiratory frequency 112.
• information representative of the blood pressure 15 information representative of the heart rate 16
• - information representative of the actimetry 17 information representative of the respiratory amplitude 111
• one of this information may not be considered, in a degraded embodiment.
• blood pressure information a particular problem is encountered, since the device of the invention is not perfectly immobilized against the subject's body, for example using adhesives. .
• the pressure applied by the case to the subject's skin can vary, either because it moves slightly, or because the tightening changes (in the In the case of a bracelet, it can slide along the wrist towards a place where the circumference of the wrist is smaller. The pressure is then less strong).
• This pressure on the skin has a direct link with the amplitude of the measured signal. It can be seen that the more pressure the casing exerts on the skin, the higher the variations in blood pressure. These variations in level should of course not be interpreted as variations in blood pressure. To avoid this problem, the device of the invention proposes to take account of information 18 representative of this pressure carried out by the housing. It may for example be a measure of tightening the bracelet.
• the variation in amplitude of the signal is directly linked to blood pressure. It suffices to measure the amplitude of the signal from the sensor to obtain information on the blood pressure while ensuring the stability of the stress induced by the bracelet.
• the information 15 to 17 is then transmitted to means 19 for analysis, and for example in the embodiment described, for recognizing the phases of sleep.
• These recognition means 19 can in particular compare the information 15 to 17 with different threshold values, deduced from the literature.
• correction and adjustment means are used, which for example implement a likelihood algorithm. They can also take account of the evolution over time of the information 15 to 17. An example of recognition is described more precisely below.
• a device therefore comprises: - measuring means, grouped in a case held on the wrist or at any point of the body where the necessary parameters can be measured.
• This case can be held by a bracelet ensuring permanent contact with the wrist.
• the measurement means notably comprise sensors (blood pressure sensor, movement sensor, bracelet tightening sensor) and electronic packaging means.
• the A / D conversion of the signal may be in the housing or in the processing means according to the chosen architecture; processing means, which can be external (microcomputer), or integrated into an ASIC type assembly placed in the housing or any other means allowing an algorithm to be applied depending on the application; a link between the above means which can be either a cable, or an optical or radio link in amplitude modulation or in frequency modulation. This connection is essential when the processing means are not included in the housing. In all cases, several boxes can be coupled to a single processing means and vice versa.
• FIG. 2 represents (in section) an example of a cardiac activity sensor which can advantageously be used in the device described above.
• An element 21 of piezoelectric ceramic is bonded by its two ends 21A, 21B to a printed circuit 22, in which it has previously been formed one day 23 allowing the element 21 to deform.
• This element 21 has for example a size of 12 x 4 x 0.7 mm.
• the sensitivity of this piezoelectric cell 21 is between 1 and 10 mm Hg, or between 1.3 and 13 kPa.
• a wedge 24 is fixed, by gluing, to the center of the element 21.
• a plate 25 of aluminum, or any other material On the wedge 24 takes place a plate 25 of aluminum, or any other material.
• This plate 25, which may have a surface of 7 ⁇ 7 mm, is in contact with the skin 26 of the subject, when the device is in place. The large contact surface makes it possible to obtain a high-power movement signal.
• the movement of the skin is transmitted to the element 21, via the shim 24. This induces a bending of the element, revealing a potential difference between the two faces of the element 21. This is this potential difference which is supplied to the signal processing module 14 of FIG. 1.
• the senor comprises a second group of piezoelectric elements
• the free plate 28 provides a signal reflecting the movements of the arm, movements which induce non-useful signals (parasites) in the first sensor.
• a reduction of these parasites can be obtained by combining the signals delivered by the two elements 21 and 27 (subtraction from the second to the first).
• the second group or “parasitic noise sensor” can also be positioned in a different way, at the level of the attachment of the bracelet to the case.
• the ceramic then works in traction-compression, and no longer in bending, and thus better captures the disturbances produced by the pressure variations on the first sensor (always applied to the skin) while being isolated from the useful signal (heart rate).
• the two bimetallic strips (or piezoelectric elements) 21 and 27 are identical and compensated for acceleration. They are mounted in opposition.
• the elements 21 and 27 are glued directly, by their ends, to the printed circuit 22, using a conductive glue. Thus, no means of wedging or fixing is necessary, nor any means of wiring. Other, more conventional techniques can also be used.
• the various electrical circuits are advantageously components 29A, 29B mounted on the surface (C.M.S).
• the sensor can therefore be represented, electrically, by the equivalent diagram in FIG. 3, associated with amplifiers.
• the cells 21 and 27 correspond to two capacitors in series 31 and 32.
• the signal 33 taken from the capacitor 32 is amplified by the amplifier 34, which delivers a signal 35 representative of the subject's movements.
• the signal 36 taken from the capacity 31 is also amplified by an amplifier 37 delivering a signal 38 corresponding to the movements and variations in the arterial pressure.
• a signal 39 representative of the arterial pressure the signal 35 (movements) is subtracted from signal 38 (movements + blood pressure) by a differentiator 310.
• the signal 35 is transmitted (311) to the processing means.
• the signal 13 in FIG. 1 corresponds to the combination of the signals 39 and 311.
• the gains Gl and G2 are different because the sensitivities of the two sensors are different : the fact that the second piezoelectric cell is isolated, while the first undergoes wrist pressure.
• the gain G3 is chosen so as to deliver a signal having good dynamics for the analog / digital conversion.
• the piezoelectric cells can for example be produced from the PXE 5 ceramic distributed by RTC (registered trademark).
• Figure 4 shows schematically a device according to the invention, in the format of a wristwatch.
• the overall device is advantageously integrated in a case 41 held on the wrist using a bracelet 42.
• Three pieces of information must therefore be measured: the pressure + movement 43 assembly; movement alone 44; the stress 45 carried out by the bracelet on the wrist (tightening) 45.
• the measurement of data 43 and 44 has been described in connection with FIGS. 2 and 3.
• the stress measurement cell 45 must be sensitive to the continuous component.
• a low-pass sensor measuring the DC component and the stress fluctuations with different sensitivities
• a low-pass sensor measuring only the continuous component exerted by the wrist on the blood pressure sensor
• a low-pass sensor measuring the stress of the bracelet. Its dynamics must be around 100 mm Hg or 13 kPa.
• the detection of the stress 45 can be done using a sensor or a force pressure sensor which is less sensitive than the arterial pressure sensor (for example a piezoresistive gauge).
• it can be registered resistors, such as MOTOROLA (registered trademark) resistors referenced MPX2040D.
• a displacement sensor knowing that it is a function of the stress applied to the wrist (the elongation of the bracelet indeed corresponds to the position of the bracelet, therefore to the pressure of the case on the skin) .
• a displacement sensor is fixed on the one hand to the housing 41, and on the other hand to the bracelet 42. The tension undergone by this sensor is directly representative of the tightening.
• a first piezoelectric element 51 therefore detects pressures 52 corresponding to the movements and to the arterial pressure. It generates a corresponding electrical signal 53 which is digitized, using an analog / digital converter 54.
• a second piezoelectric element 55 detects movements alone
• the corresponding electrical signal 57 is also digitized, by the analog / digital converter 58.
• the two ADCs 54 and 58 sample the signals for example at a rate of 64 measurements / s. They can advantageously constitute two channels of a converter also taking care of the conversion of the tightening stress.
• the difference 59 is then made between the digital signals 510 and 511, to obtain the digital signal 512 representative of the arterial pressure alone.
• this subtraction can be twofold: first of all a wired subtraction is carried out, as illustrated in FIG. 4. In general, the resulting signal remains disturbed by the movements; - a second software subtraction is therefore carried out. To do this, a third analog / digital converter digitizes the signal "movements + blood pressure" delivered by the first piezoelectric element. The processing then consists in searching for the correlations between the two digitized signals, then in removing from the "arterial pressure" signal which corresponds to the movements.
• This signal 512 is transmitted to a module 513 for linearization, low-pass filtering and / or adaptive filtering and scaling.
• the module 513 is also supplied by the signal 51 1, to perform a search and a removal of the correlations between the two signals 511 and 512.
• Scaling consists in multiplying the value received by a sensitivity coefficient representative of the device.
• the corresponding signal 514 may for example be as shown in FIG. 6.
• FIG 6 which shows the evolution of blood pressure as a function of time, we can distinguish: - systolic pressure (SBP); diastolic pressure (DBP); mean blood pressure (MBP).
• SBP systolic pressure
• DBP diastolic pressure
• MBP mean blood pressure
• SBP systolic pressure
• a correction module 517 determines information 518 representative of the relative arterial pressure of the subject (comprising at least one of the data: SDP, DBP, MBP).
• the correction has two levels: application of a likelihood algorithm (in particular making it possible to eliminate visibly erroneous data); - correction depending on the stress exerted by the bracelet (tightening).
• a tightening (or pressure) sensor 519 is implemented, delivering a signal 520 which is digitized (521) before being transmitted (522) to the correction module 517.
• the heart rate (or pulse) is then determined from information 514 on blood pressure. This operation consists in measuring the period of the fundamental (61, figure 6) contained in the blood pressure signal.
• the analysis band is narrow and that there is only search for the fundamental, an approach of calculation by multichannel filtering 523 is desirable. Indeed the analysis band is from 30 beats / s to 240 beats / s or 0.5Hz to 4Hz.
• This method has the particularity of consuming little memory capacity and in number of operations to be executed taking into account the frequencies of each channel 524 1 to 524 N which can be 0.5 0.66 0.8 1 1.33 2 4 Hz, corresponding to heart rates of 30, 40, 48, 60, 80, 120 and 240 beats / min.
• Each channel corresponds to a sub-multiple flow rate of the maximum rate.
• only one filter template is used.
• the signal energy and the period of the filtered signal are calculated (525) by counting. We thus obtain a spectrum of energy lines and a function of calculated periods.
• a selection strategy 525 determines the most reliable channel, and delivers the corresponding information 526 to the module 527 for recognizing sleep phases.
• the method consists in, on a sliding window of duration 8 s for example, or of the same duration as the respiratory period, apply a mathematical operator which calculates the period or the frequency of the blood pressure signal, then the variance from what we will estimate the standard deviation or variability.
• Mathematical operators can be: an autocorrelation function, a multichannel filtering, a partial autocorrelation calculation with monitoring of the minimum and maximum peaks, a spectral estimation.
• the respiratory parameters 545 are then calculated. We seek (547) the maxima of the blood pressure signal (amplitude and coordinates in time). Then, we delete (548) the average value and, by detecting the zero crossings of the signal, we calculate the respiratory period 545 and its inverse, the frequency. Over the duration of this period, the average value of the rectified signal is calculated, which is a good image of the respiratory amplitude 545.
• a subsampling (1/8) is performed 546 on the motion signal then a rectification and a low-pass filtering.
• the calculated average value is proportional to the amplitude of the average acceleration during a given window, in the direction perpendicular to the inside of the wrist.
• the energy of the movement is calculated after integration of the sub-sampled signal 51 1. Then, we straighten the signal and apply a low-pass filter to it and calculate the average which is proportional to the average speed, in the previous direction and on the same window. The energy, proportional to the square of the speed, is then calculated if necessary.
• the module 527 therefore receives four pieces of information: arterial pressure 518; - heart rate 526; actimetry 544; respiratory parameters (frequency and amplitude) 545. In simplified embodiments, it is of course possible to ignore all of this information. The validity of this information has been verified in a medical environment, in particular at CHR Kergormar de Lannion and CHR de Brest, by comparison with signals measured using conventional medical sensors (sysmographs. Respirographs, ).
• the module 527 calculates the variations of different information which make it possible to determine the sleep phase. Each of this information is for example compared to one or more thresholds characteristic of the different sleep phases. The results of these comparisons are then correlated to each other to determine the current 528 sleep phase.
• a likelihood algorithm is used to control the reliability of the recognition.
• This sleep phase information 528 can be viewed, for example using a liquid crystal display 529. It is also stored in storage means 530. These can also store the different information 511, 518 and 527, 544, 545.
• the outputs can be: - a watch-type display, an audible or luminous alarm clock, a paper trail, a memorization, an appliance command, - etc ...
• the stored data 531 make it possible to perform statistics 532, the results of which 533 can be viewed, but above all used in a module 534 for prediction. It is thus possible to generate an alarm signal 535, producing an audible signal 536, when the evolution of the arterial pressure and / or of the heart rate presents characteristics dangerous for the subject. It should be noted that this prediction module is very important, because it is not the absolute values of the signals but their changes over time that are significant.
• the device can include connection means 537, which make it possible to transmit the content of memory 530 to an external processing unit.
• the link can be wireless.
• the RF link may implement an amplitude modulation (ASK mode).
• the transmitter in the housing
• the transmitter includes, for example, a local oscillator with a surface wave vibrating at 224.5 MHz. At this frequency, the transmitting antenna is of reduced dimensions (a few cm on one side) and can be produced on the printed circuit.
• the transmitter After the transmission of a measurement, the transmitter is put on standby, which reduces current consumption.
• the transmitter power can be less than 5 mW and its range a few meters.
• a "super-reaction" type receiver can be chosen with a local oscillator at 213.8 MHz and an intermediate amplification at 10.7 MHz followed by decoding.
• FIG. 9 shows, in another form, the treatments carried out in a device according to the invention.
• the processing means are separated from the autonomous housing carrying the sensors (the same processing can of course be carried out internally directly in the housing).
• the measurements carried out are received over the air using an antenna 91.
• a receiver / decoder 92 restores, from the received signal 93, a signal representative of the movement 94, a signal representative of the pulse 95 (corresponding to the subtraction signals from the two sensors) and a signal representative of the stress (tightening of the bracelet) 96.
• an adaptive filtering 912 is performed to subtract the residual noise due to the movements, then a high-pass filtering 913 to remove the low residual frequency.
• the filtered signal 914 makes it possible to calculate (915) the average pulse 916 and the order moment 2 917 representative of the average pulse.
• the average pulse may be displayed (918) for example every 10 or 20 seconds.
• the filtered signal 914 used for the pulse is also used for the blood pressure.
• it undergoes a complementary low-pass filter 919 for refining the band to be analyzed, then a statistical calculation of amplitude 920 (histogram), filtering 921 and detection 922 of the extremes.
• the signal 926 representative of the pulse obtained after the double subtraction of the noise is subjected to a detection of the extremes 927, then to a suppression 928 of the average value.
• the mean value of the signal which provides information 930 representative of 1 " respiratory amplitude
• (931) the period of the signal which corresponds to the respiratory period.
• FIG. 8 illustrates an example of operation of this module 923 in the case of the recognition of the sleep phases.
• the recognition process works in two parts: the first part, called “learning", is done before trying to recognize the phases of a patient's night's sleep. In this part, we look at the distribution of the different measurements made on these two respiratory parameters, in a representation space which has as axis the two variables respiratory rate 72 and respiratory amplitude 73. We also know the exact belonging of all these measures to the different phases of sleep (awakening 74, REM sleep 75. light slow sleep 76, deep slow sleep 77).
• recognition of sleep stages a recognition rate of the order of 85% can be achieved, which opens the field to new applications.
• drowsiness application this application is very extensive and requires substantial research as well as the carrying out of comparative measurements.
• the state of drowsiness is a transitional state between wakefulness and light slow sleep - stage 1.
• the cardiac activity is modified and the processing of new information carried out by an easily portable sensor would be very appreciated.
• sleep quantification From a good recognition we can sum the duration of the different stages, appreciate the different sleeps in kind and in duration and deduce possible troubles. Analysis of sleep throughout the night can facilitate a pre-diagnosis in certain diseases (sleep apnea) for example.
• Heart disease is the leading cause of permanent disability in adults under the age of 65 (responsible for 50% of hospital days in the US), according to "Heart disease, hypertension & food "by Alison Hull (editions of Trécarré).
• the prevention of these ⁇ by a portable and user-friendly device therefore represents an advance in the detection of these diseases.
• the device according to the invention can also make it possible to program a biological wake-up time.
• programming means 538 make it possible to define a time interval and a sleep phase 539 during which one wishes to be awakened.
• the alarm clock is desired in correlation with a sleep phase
• the alarm clock is programmed by push buttons like on a classic watch.
• a module 540 for determining the time of awakening can then generate an alarm 541, as a function of this programming 539, of the recognized sleep phase 528 and of the time 542 provided by a clock 543 (which also advantageously offers all the watch functions).
• This second application which can be combined or distinct from the previous ones, may for example be of interest: hypnologists (treating sleep disorders) for the problems of their patients, who cannot keep an account of their hours of sleep.
• hypnologists treating sleep disorders
• One or more nights in the hospital are so far necessary to collect scientific data. This obviously costs a lot of money for biased reliability, because the patient is removed from his environment, which greatly disrupts his sleep; - cardiologists, to monitor the cardiac effort of their patients throughout the day; individuals with work overload for a few days, and would like not to waste time dreaming (students, liberal professions, military or navigators ...); - heart patients, who must limit their efforts.
• the invention can report a breach of threshold or accumulated fatigue; people who want to split their sleep times and take a nap, and want to limit the nap to the most important cycle and have a short nap and a quick wake up; - people having trouble getting up! people with an interest in their dreams; people who want to be able to better manage their efforts, their recovery and their food; etc.
• Other applications of the invention may also be: learning.
• Certain periods of sleep (REM sleep) are conducive to receiving school or other information. The triggering of a sound device during REM sleep is possible. - quantification of sleep. The amount of sleep (duration and structure) is a determining factor in observing its shape. This is why it is interesting to know the structure of his sleep.
• the curve of Figure 8 shows the evolution of the 3 signals (81 - blood pressure, 82 - movement, 83 - tightening of the bracelet) during a night period. It is observed that during 8 cardiac pulses, the blood pressure signal is flat 84 (absence of modulation), which shows the cessation of breathing. At the same time, the amplitude 85 of this signal increases by 25% while the bracelet tightening is stable. This means that respiratory arrest is accompanied by an increase in blood pressure.
• the respiratory half-period 86 and the respiratory amplitude 87 are also easily distinguished on this diagram (in practice, these data are of course determined over a longer period). This has already been observed during apnea but never by continuous measurements (only by tourniquet), which limits the interpretation of the measurements. For the moment, apnea is detected using heavy equipment and only in hospitals.
• pig slaughterers like to know that slaughtered pigs have had a "normal" life (no disease, therefore no treatment). By monitoring the sleep of the animal and its temperature, they can claim to treat meat of known quality. In addition, the diurnal and nocturnal behavior of the animal depends on the diet, hence the advantage which can be drawn from the behavioral monitoring of the animal. Furthermore, numerous adaptations of the invention can be envisaged, both with regard to the types of sensor (s) used, the supports of the invention (bracelets, rings, necklaces, adhesive systems, etc.) or the types of treatments and / or calculations made from signals from sensors.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Cardiology (AREA)
• Veterinary Medicine (AREA)
• Public Health (AREA)
• Physics & Mathematics (AREA)
• General Health & Medical Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Molecular Biology (AREA)
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• Anesthesiology (AREA)
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• Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)
• Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)

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• 1993
  • 1993-01-28 FR FR9301132A patent/FR2700683B1/fr not_active Expired - Fee Related
• 1994
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